1 Final Draft Staff Report with Appendices 

 For Proposed Amendments to Rule 4684 

SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

FINAL DRAFT STAFF REPORT 

Proposed Amendments to Rule 4684 

(Polyester Resin Operations) 

August 18, 2011 

Prepared by: Nichole Corless, Air Quality Specialist 

Reviewed by: Yousif Zardo, Air Quality Inspector 

James Harader, Senior Air Quality Engineer 

George Heinen, Rule Development Supervisor 

 Errol Villegas, Strategies and Incentives Manager 

 Samir Sheikh, Director of Strategies and Incentives 

I. SUMMARY 

A. Reasons for Rule Development and Implementation 

The California Air Resources Board (ARB) and the United States Environmental Protection 

Agency (EPA) classified the San Joaquin Valley Air Basin (SJVAB) as severe and extreme 

non-attainment for the state and federal ozone standards, respectively. In accordance with 

Federal Clean Air Act (CAA) requirements for non-attainment areas, the San Joaquin Valley 

Unified Air Pollution Control District (District) adopted the 2007 Ozone Plan to establish a 

strategy for attaining the eight-hour ozone standards. 

The ozone attainment strategy is comprised of regulatory and incentive-based measures to 

reduce emissions of nitrogen oxides and volatile organic compounds (VOC), a precursor of 

ground-level ozone. Rule 4684 (Polyester Resin Operations) controls VOC by limiting the 

VOC content of materials, specifying control system requirements, and requiring loss 

minimizations practices. On September 17, 2009 the San Joaquin Valley Unified Air 

Pollution Control District’s (District) Governing Board amended Rule 4684 to satisfy 

commitments in the District’s 2007 Ozone Plan and implement RACT requirements as 

recommended in the Control Techniques Guidelines (CTG) for Fiberglass Boat 

Manufacturing Materials (EPA-453/R-08-004) (Appendix E). On January 26, 2010, the 

United States Environmental Protection Agency (EPA) found that the current Rule 4684 

“strengthens the SIP and largely fulfils the relevant Clean Air Act requirements.” However, 

EPA also determined that additional review was required to ensure that RACT requirements 

are satisfied for fibreglass non-boat manufacturing operations, and suggested consideration 

of additional requirements through their Technical Support Documents (TSD). As such, 

EPA issued a limited approval/limited disapproval of the rule (Federal Register Vol. 75, 

No.16 as 40 CFR Part 52). A copy of this Federal Register publication is included as 

Appendix C of this Staff Report. 
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These amendments will address the recommendations in EPA’s Technical Support 

Document (TSD) and end the 18-month sanction clock associated with the EPA action. 

B. Description of the Rule Development Project 

The purpose of this rule development project is to amend Rule 4684 update rule language 

as identified in the TSD published by EPA in May 2009 (Appendix D). According to the 

TSD, the District must consider revising the current monomer content limits to be as 

stringent as other California Air Districts to fulfill RACT requirements. As part of those 

amendments, new rule definitions would also be added to clarify and support the monomer 

content limit changes. Also, in our continuing effort to provide excellent customer service to 

the affected stakeholders, amendments will also remove past deadlines in the current rule 

language to streamline the rule requirements and aid in rule compliance. 

C. Rule Development Process 

As part of the rule development process, District staff contacted operators and requested 

information to assess the impact of potential rule amendments to the VOC content limits of 

materials. Based on these conversations, the majority of operators will not encounter 

problems complying with the draft amendments. District staff held a public review period 

and technical workgroups to allow public review and comment on the draft amendment 

language and this staff report. Comments received were incorporated into the proposed 

rule and final draft staff rule, as appropriate. 

The proposed rule and final draft staff report were published and provided to affected 

sources and interested parties prior to the public hearing to consider the adoption of the 

rule by the District’s Governing Board. The proposed amendments were scheduled to be 

presented to the Governing Board at their June 16, 2011 meeting for the public hearing to 

consider adoption. 

II. CLIMATE CHANGE 

The California Global Warming Solutions Act of 2006 (AB 32) created a comprehensive, 

multi-year program to reduce greenhouse gas (GHG) emissions in California, with the 

overall goal of restoring emissions to 1990 levels by the year 2020. In the coming years, 

ARB and the Legislature will be developing policies and programs to implement AB 32. 

The District believes that the evidence and the rationale that climate change is occurring is 

compelling and convincing. In addition to the long-term consequences of climate change, 

the District is concerned with the potential ramifications of more moderate but imminent 

changes in weather patterns. The Valley depends heavily on agriculture for its economy 

and has developed agricultural practices based on the last several decades of weather 

patterns. Unanticipated and large fluctuations in these patterns could have a devastating 

effect on the Valley’s economy. 
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While there are many win-win strategies that can reduce both GHG and criteria/toxic 

pollutant emissions, when faced with situations that involve tradeoffs between the two, 

District staff believes that the more immediate public health concerns that may arise from 

an increase in criteria or toxic pollutant emissions should take precedence. 

III. BACKGROUND 

EPA Recommendations 

On January 26, 2010 EPA published a limited approval and limited disapproval of 

revisions to the District portion of the California SIP in the Federal Register regarding 

VOC emissions from polyester resin operations. Under authority of the CAA, as 

amended in 1990, this action simultaneously approves local rules that regulate these 

emission sources and directs California to update rule language. 

EPA finalized a limited approval of the submitted rule, as authorized in §110(k)(3) and 

§301(a) of the CAA; EPA also simultaneously finalized a limited disapproval of a 

portion of the rule. Because of the limited disapproval, sanctions will be imposed on 

the District unless EPA approves subsequent SIP revisions within 18 months of the 

effective date of their final action. These sanctions will be imposed under §179 of the 

CAA according to 40 CFR 52.31. In addition, EPA must promulgate a federal 

implementation plan (FIP) under §110(c) unless EPA approves subsequent SIP 

revisions that update rule language within 24 months of the effective date of this 

action. EPA’s final limited disapproval does not prevent the District from enforcing the 

current rule, as adopted by the Governing Board. 

The TSD for EPA’s Notice of Direct Final Rulemaking recommends the following language 

updates: 

1. Other California air districts have more stringent monomer content requirements 

than Rule 4684. The District must either lower specific monomer content limits to 

be as stringent as similar categories in other air districts or demonstrate that the 

more stringent limits are not economically or technologically feasible for the sources 

in the Valley. 

2. Other California air districts require a 90% overall capture and control efficiency 

requirement for VOC control systems, compared to the 85% requirement in Rule 

4684. The District must either match other air districts and not limit the use of these 

systems to continuous periods of operation or demonstrate that the more stringent 

limit is not economically or technologically feasible for the sources in the Valley. 
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IV. CURRENT RULE 4684 AND PROPOSED AMENDMENTS 

A. Current Rule 4684 

Rule 4684 was adopted on May 19, 1994. The rule has undergone three amendments, 

with the last occurring on September 17, 2009. The last rule amendments incorporated 

the CTG monomer content limits as applicable to fiberglass boat manufacturing materials. 

The purpose of the rule is to limit VOC emissions from polyester resin operations and from 

organic solvent cleaning, storage and disposal of solvents and waste solvent materials 

associated with such operations. The rule applies to commercial and industrial polyester 

resin operations. Polyester resin operations is defined in the rule as methods used for the 

production or rework of products by mixing, pouring, hand layup, impregnating, injecting, 

forming, winding, spraying, and/or curing with fiberglass, fillers, or other reinforcement 

materials and associated cleanup. 

Rule 4684 exempts low-emitting operations such as facilities that use less than 20 gallons 

per month of polyester resin, provided the operator keeps the records required by the rule 

to demonstrate exemption status. The rule also exempts specialty applications such as 

cleaning of solar cells, laser hardware, scientific instruments, or high precision optics, and 

cleaning in laboratory tests and analyses, or bench scale or research and development 

projects from the organic cleaning material requirements. 

The current Rule 4684 allows a general polyester resins operator to choose one of three 

equivalent compliance methods: 

• Use low-VOC polyester materials, ranging from 35% to 50% by weight monomer 

content, depending on whether the material is a resin or gel coat; 

• Use resins containing vapor suppressant resulting in a weight loss from VOC 

emissions that does not exceed 60 grams per square meter of exposed surface 

during resin polymerization; 

• Use a closed-mold system; or 

• Operate an APCO-approved VOC emission control system that achieves an 

overall capture and control efficiency of at least 85 percent by weight. 

Fiberglass manufacturing operators must comply with the recently adopted monomer 

content limits specified for fiberglass boat manufacturing operations in the EPA CTG. 

To minimize emissions by reducing overspray, Rule 4684 requires that spray application of 

resins be performed using airless, air-assisted airless, high-volume low-pressure spray 

equipment, or electrostatic spray equipment. In lieu of using the specified spray 

equipment, the operator may comply by operating an APCO-approved VOC emission 

control system around the application operation, provided the control system achieves an 

overall capture and control efficiency of at least 85 percent by weight. 
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Rule 4684 requires operators to use organic solvent cleaning materials that contain no 

more than 25 grams/liter (0.21 pound/gallon) for all types of cleaning operations. Also, the 

rule includes administrative requirements such as recordkeeping and test methods to 

demonstrate compliance with the emission standards of the rule. 

 

For detailed requirements, please refer to the current Rule 4684, which is available on the 

District’s website at www.valleyair.org. 

B. Proposed Amendments to Rule 4684 

As discussed in the TSD, current monomer content limits and VOC control system 

effectiveness should be revised to be as stringent as other air districts to fulfill RACT 

requirements. District staff compared our limits to those in other air districts and produced 

a draft, revised VOC limit table for resins and gel coats. The revised table was compared 

to current operator information from our Permits database. Operators that would have to 

comply with the draft VOC limits were contacted. Based on the research and industry 

contacts, operators will be able to comply with draft changes without encountering 

problems or incurring substantial costs. According to our conversations with the 

operators, they are either currently using coating that are compliant with the new limits, 

don’t use coating in the new categories that are being added, or can switch to compliant 

coatings without significantly impacting their operations. 

The monomer content limits for polyester resin operations does not include changes to 

fiberglass boat manufacturing limits, because these limits were previously addressed in 

the last rule amendments. Staff proposes to make the amendments effective on and after 

January 1, 2013 to allow time for rule dissemination and the operators to take any 

necessary compliance actions. As part of these amendments, new rule definitions would 

be added to clarify and support the monomer content limit changes. Also, in our continuing 

effort to provide excellent customer service to the affected stakeholders, proposed 

amendments would also remove past deadlines in the current rule language to streamline 

the rule requirements and aid in rule compliance. 

The following specific changes are contained in the proposed amendments: 

• Section 3.0 (Definitions) would include new definitions of terms associated with new 

material categories in order to enhance the clarity and effectiveness of the rule. 

Definitions were added for the following terms: Corrosion-Resistant Material; Filament 

Application; Filled Polyester Resin Material; Filler; Fire Retardant Material; Fluid 

Impingement Technology; High-Strength Material; Lamination Resin; Manual 

Application; Marble Resin; Non-Atomizing Spray Gun; Production Resin; Small Job; 

Solid Surface Resin; Specialty Gel Coat; Touch Up; and Tub/Shower Resin. For 

consistency, these definitions were primarily derived from those found in other air 

district rules and in 40 CFR 63.5935. 
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• Section 5.0 (Requirements). Section 5.1, Table 1, would be added to specify the new 

material VOC content limits that would be effective after January 1, 2013. This 

compliance date is to allow time for rule dissemination and for any existing stocks of 

older materials to be depleted. Existing material VOC limits would remain in effect until 

that date, however, to prevent any rule relaxation. 

The proposed limits are the most stringent limits currently in place in any air district. 

The process for determining the following proposed lower monomer content limits is 

further discussed in Section X of this Staff Report. Because the limits have been in 

place for some time in other air districts, material availability is generally expected to be 

adequate and compliance with the rule should not pose a hardship to operators. Staff 

verified with operators that they are either currently using compliant materials, don’t 

use the specialty products, or can switch to such materials without significant impacts 

to their operations. These limits represent the most stringent limit in place in any air 

district, so the proposed rule should satisfy, if not go beyond, RACT for this category. 

Table 1: Compliant Materials Weighted Average Monomer VOC Content 

for Open Molding Resin and Gel Coat

Material 

Weight Percent Limit on and after 

January 1, 2013 

a. General Purpose Resin 

 - Marble Resins 10% or 

32 % as supplied, no fillers 

 - Solid Surface Resins 17% 

 - Tub/Shower Resins 24% or 

35 % as supplied, no fillers 

 - Lamination Resins 31% or 

35 % as supplied, no fillers 

b. Tooling Resin 

 - Atomized (spray) 30% 

 - Non-atomized 39% 

c. Specialty Resin 

 - Fire Retardant Resin 38% 

 - High Strength Materials 40% 

 - Corrosion Resistant Resin 48% 

d. All Other Resin 35% 
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Table 1: Compliant Materials Weighted Average Monomer VOC Content 

for Open Molding Resin and Gel Coat (continued)

Material 

Weight Percent Limit on and after 

January 1, 2013 

e. Tooling Gel Coat 40% 

f. Pigmented Gel Coat 

 - White and Off White 30% 

 - Non-White 37% 

 - Primer 28% 

g. Clear Gel Coat 

 - Marble Resins 40% 

 - Other Resins 44% 

h. Specialty Gel Coats 48% 

• Section 5.1.1.3 would be modified to lower the VOC emission limit of 60 grams per 

square meter to 50 grams per square meter when using a resin containing a vapor 

suppressant. This is level consistent with other California air districts and is currently 

achieved by Valley operators subject to this requirement. 

• Section 5.1.1.5.2 would be modified to remove the reference to “continuous operation”, 

as required by EPA, since other districts did not have this qualifying language in their 

rules. This language was ambiguous as it might have been interpreted as the 

condition under which the control system would either be operated or tested. Section 

6.1.1.4 already required that the system would have to be operated “during periods of 

emission producing activities” so this proposed amendment does not change the 

stringency of the rule or affect Valley operators. Based on staff conversations with 

EPA, as a clarification, a reference to the test methods in Section 6.2 has been added. 

Section 5.1.1.5.2 would also be modified in response to EPA comments, to change the 

emission control system limit from 85% control efficiency to 90% control efficiency to 

reflect the limit in other air districts. Operators who are currently using an emission 

control would either be able to comply with one of the other options, such as meeting 

the proposed monomer content limits, or are boat manufacturers and therefore subject 

to the fiberglass boat manufacturing limits instead. One operator recently replaced 

their carbon adsorption system with a regenerative thermal oxidizer (RTO) system and 

is still testing the efficiency. Typical RTO VOC control efficiency is much higher than 

carbon adsorption systems, so the change in rule language should not present a 

problem. The operator should also be able to comply under other sections of the rule. 

In general, operators using a VOC emission control system would be able to comply 

with the amended rule requirements using their current equipment. 
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• Section 5.1.1.6 would be added to address special considerations for minor touch ups, 

repairs, and small jobs. This allowance is similar to other air districts and was 

requested by stakeholders to minimize material waste. Such material can have up to 

10% higher monomer for proper operation in this equipment. The proposed new 

section would allow operators to use hand-held atomized spray equipment for small 

projects, up to two gallons per day per facility. This allowance is needed because 

non-atomized spray equipment is not available for small jobs that do not require large 

amounts of resin or gel coat. Non-atomizing equipment is used for large products and 

typically has long resin or gel coat hoses that can contain several gallons of resin. Use 

of this equipment for touch up, repairs, and small jobs and would lead to waste or 

inefficient operations. Small jobs would include minor operations like attaching 

supports to allow for custom mounting of special-order hardware. 

Some districts, such as Bay Area address these situations by stating the equipment to 

must be limited to equipment with one quart reservoirs, but do not specify a limit on the 

total material used per day. Therefore, the proposed rule language would be more 

stringent by establishing a limit in the amount of material that can be used per day at a 

facility. Recordkeeping for this allowance would also be added to Section 6.1 to allow 

verification and enforcement. 

• Section 5.2 would be clarified by removing language referring to old implementation 

dates for fiberglass boat manufacturing operations. Compliance with these sections 

has been required of applicable operators since January 1, 2011, so removal of the 

dates does not affect rule stringency. 

V. VOC EMISSION AND REDUCTIONS

According to the District’s 2007 Ozone Plan, the source category for Polyester Resin 

Operations (S-IND-3) was not recommended as a control measure for VOC reduction and 

no additional reductions were available. Since the federal CAA requires ozone 

nonattainment areas to implement RACT, the proposed amendments are required to meet 

the stringency of other California air districts. 

The ARB emissions inventory shows total VOC emissions of only 0.38 tons of VOC per 

day for this source category, based on actual material usage and VOC contents. District 

staff believes that further VOC emissions reductions as a result of this rulemaking project 

will be insignificant since most operators are already in compliance with the proposed 

amendments or do not use the specialty categories materials which are being modified. 

For the most common categories, the difference in VOC content is approximately 14% so 

if operators were not already complying with the proposed limits, the maximum reduction 

would be 0.05 tons of VOC per day. Given that the amount of operators in compliance 

and that some of the operators are fiberglass boat manufacturers who are already in 

compliance with the previously adopted CTG limits, the actual emission reduction is 
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expected to be much less and therefore not significant and are not being claimed for this 

rule amendment project. No SIP commitment exists for this project so no impact is 

expected on attainment progress. 

VI. COST EFFECTIVENESS ANALYSIS 

Pursuant to California Health & Safety Code Section 40920.6(a), the District is required to 

analyze the cost effectiveness of new rules or rule amendments that implement Best 

Available Retrofit Control Technology (BARCT) or planning requirements to incorporate all 

feasible measures. The proposed amendments to Rule 4684 would only add federal RACT 

requirements but not BARCT or all feasible measures, and are therefore not subject to the 

cost effectiveness analysis mandate. Given that operators are generally complying with the 

new limits currently and there are no significant emission reductions or compliance costs 

expected from these rule changes, a cost effectiveness analysis has not been performed. 

VII. SOCIOECONOMIC ANALYSIS

Pursuant to California Health and Safety Code (CH&SC) 40728.5(a), “Whenever a district 

intends to propose the adoption, amendment, or repeal of a rule or regulation that will 

significantly affect air quality or emissions limitations, that agency shall, to the extent data 

are available, perform an assessment of the socioeconomic impacts of the adoption, 

amendment, or repeal of the rule or regulation. This section does not apply to the 

adoption, amendment, or repeal of any rule or regulation that results in any less restrictive 

emissions limit if the action does not interfere with the district's adopted plan to attain 

ambient air quality standards, or does not result in any significant increase in emissions.” 

This rule-amending project does not significantly affect air quality and no significant emission 

reductions are expected or claimed. Although, some emissions limitations are amended, the 

revisions are not considered significant, since the limits have been in place for some time in 

other air districts and compliant material availability is expected to be adequate. 

Based on discussions with operators, the changes do not create a significant change to their 

operations or economic situation since they are already using compliant materials or do not 

use the specialty materials that are being impacted. Therefore, staff concludes that, if a 

detailed socioeconomic analysis were conducted, there would be no significant 

socioeconomic impact from this rule. 
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VIII. ENVIRONMENTAL ASSESSMENT 

Pursuant to the California Environmental Quality Act (CEQA), staff investigated the likely 

environmental impacts of the proposed amendments to Rule 4684. Adoption of the 

proposed amendments would lower allowable VOC emissions limits from polyester resin 

operations, potentially having a positive impact on air quality. Because operators are 

generally already complying with the proposed limits, there are no foreseeable changes in 

operating practices resulting from implementation of these changes that would impact 

environmental resources, other than air quality. Therefore, staff concludes that there is no 

substantial evidence in the whole record before the District that the proposed 

amendments would cause any adverse environmental effects. The District finds that the 

project is exempt per the general rule that CEQA applies only to projects which have the 

potential for causing a significant effect on the environment (CCR §15061(b)(3)). For these 

reasons, staff is proposing to file a Notice of Exemption upon Board adoption of the 

proposed amendments to Rule 4684. 

IX. RULE CONSISTENCY ANALYSIS 

As required by California Health & Safety Code Section 40727.2, District staff conducted a 

rule consistency analysis in Appendix B. That consistency analysis compared the 

elements of the proposed version of Rule 4684 with the corresponding elements of other 

District rules, federal regulations and guidelines that apply to the same source category or 

type of equipment. Based on that analysis, District staff found that the proposed 

amendments to Rule 4684 would not conflict with federal rules, regulations, or policies 

covering similar stationary sources. 

X. REASONABLY AVAILABLE CONTROL TECHNIQUES (RACT) ANALYSIS 

This analysis is necessary for any rule that effects ozone, found in the Ozone plan. EPA 

partially disapproved part of Rule 4684 in January 2010 because it did not meet their 

requirements for RACT. The incorporated proposed amendments to the District Rule 

4684 meets, or exceeds RACT requirements. 

RACT Discussion 

The Clean Air Act (CAA) Section 182(b)(2) states that ozone attainment plans shall assure 

that RACT for volatile organic compounds (VOC) is applied at certain sources. Section 

182(f) extends federal RACT requirements to NOx rules and major NOx sources. District 

Rule 4684 is a VOC rule, therefore underwent a RACT analysis during this rule amending 

project. A RACT analysis requires an examination of a rule against Federal rules, 

regulations, and technology 4684 was compared to federal and state regulations and 
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guidance in the 2009 RACT SIP, Chapter 4: Rule Analysis. The following is a discussion 

of that analysis. 

District staff compared emission limits, optional control requirements, and work practice 

standards in District Rule 4684 to comparable requirements in rules from the other Air 

Districts in California nonattainment areas. The analysis shows that the current Rule 4684 

was less stringent when compared to specific requirements, discussed below, in other 

Districts’ rules. 

District staff also reviewed the Technical Support Document that EPA issued discussing 

the limited approval/limited disapproval of Rule 4684. Staff proceeded to incorporate the 

following changes that were proposed by EPA: 

• Lower VOC monomer content limits to match other air districts. 

• Increase the control efficiency requirement for VOC emission control systems. 

• Add definitions of terms associated with the new material categories. 

• Modify Section 5.1.1.2 to lower the allowable VOC emissions when using a vapor 

suppressing resin. 

• Modify Section 5.1.1.4.2 to remove the mention of “continuous operation”. 

District staff evaluated Rule 4684 in comparison with equivalent California air district rules 

and the proposed amendments will make Rule 4684 as comparable to the most stringent 

limit in other air districts. Specifically, the following air district rules were evaluated, as 

cited in the TSD: 

• South Coast Air Quality Management District (SCAQMD) Rule 1162 

• Bay Area Air Quality Management District (BAAQMD) Rule 8-50 

• Sacramento Metropolitan Air Quality Management District (SMAQMD) Rule 465 

• Ventura County Air Pollution Control District (VCAPCD) Rule 74.14 

• Mojave Desert Air Quality Management District (MDAQMD) Rule 1162 

The following table summarizes the proposed limits and indicates where the limit was 

found to be the most stringent and the year the limit went into effect in the particular 

district. The majority of the limits originate from the SCAQMD Rule 1162 which were 

effective since 2002. Subsequent to that time, other air districts have incorporated similar 

limits, as shown in Table 2. The long-term requirement and wide-spread acceptance of 

these limits indicates their general commercial availability and applicability. This was also 

borne out by staff conversations with Valley operators who verified that they are currently 

using these materials. 

Tooling resin and tooling gel coat limits were not found in other districts’ rules but are 

mentioned in the Fiberglass Boat Manufacturing CTG and are therefore considered to be 

RACT for this material type. 
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Table 2: Comparison of Proposed Compliant Materials Weighted Average Monomer VOC 

Content 

With Similar Categories in Other California Air Districts’ Rules 

Material Proposed Weight Percent 

Limit 

Districts with similar limits (effective 

date of the limits in that air district) 

a. General Purpose Resin 

 - Marble Resin 10% or 

32% as supplied, no fillers

SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005); MDAQMD (2007) 

 - Solid Surface Resin 17% 

 - Tub/Shower Resin 24% or 

35% as supplied, no fillers

 - Lamination Resin 31% or 

35% as supplied, no fillers

b. Tooling Resin 

 - Atomized (spray) 30% Fiberglass Boat Manufacturing CTG - Non-atomized 39% 

c. Specialty Resin 

 - Fire Retardant Resin 38% SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005); MDAQMD (2007) 

 - High Strength Materials 40% SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005) 

 - Corrosion Resistant Resin 48% SCAQMD (2002) 

d. All Other Resin 35% SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005); MDAQMD (2007) 

e. Tooling Gel Coat 40% Fiberglass Boat Manufacturing CTG 

f. Pigmented Gel Coat 

 - White and Off White 30% SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005); M.DAQMD (2007) - Non-White 37% 

 - Primer 28% 

g. Clear Gel Coat 

 - For Marble Resins 40% SCAQMD (2002); VCAPCD (2005); 

MDAQMD (2007) 

 - For Other Resin 44% SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005); MDAQMD (2007) 

h. Specialty Gel Coat 48% SCAQMD (2002); BAAQMD (2010); 

VCAPCD (2005); MDAQMD (2007) 
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The MDAQMD and BAAQMD have lower limits for Corrosion Resistant Resin than the 

SCAQMD, depending on the application method, as shown in Table 3. 

Table 3: Comparison of Corrosion Resistant Resin Limits 

Material Category Monomer VOC 

Content Limit 

District 

(effective date of the limit) 

 - Corrosion Resistant Resin 48% SCAQMD (2002) 

 -- Non-atomized 46.2% MDAQMD (2007) 

 -- Non-atomized 46% BAAQMD (2010) 

 -- Filament Application 42% BAAQMD (2010); MDAQMD (2007) 

 -- Manual Application 40% BAAQMD (2010); MDAQMD (2007) 

It would normally be reasonable to lower a material’s VOC content for operations which do 

not require lower viscosity to aid in application. However, staff received a comment from 

an operator that corrosion resistant resins must have a sufficient number of styrene 

molecules to complete all of the desired number of cross-links and create the required 

corrosion-resistance and mechanical properties. The required styrene is contained in the 

VOC used in the resin system and becomes an integral part of the final cured composite. 

Reducing the VOC levels to the BAAQMD and MDAQMD would reduce the styrene levels 

below what is required to form the necessary cross-links and would make such operations 

technologically infeasible in the Valley. 

This concern is supported by the SCAQMD rule history which originally set the Corrosion 

Resistant Resin limit at 30%. SCAQMD determined that the low limit was technologically 

infeasible for this category and settled on a 48% limit to account for the special physical 

and chemical considerations of this material. MDAQMD staff confirmed that they did not 

have an operation in this category and that no operators had used this material, so their 

limits cannot be considered to be an achieved-in-practice RACT standard. Staff therefore 

proposes to apply the SCAQMD limit for this category, regardless of application method. 

This limit would avoid an extreme impact on the existing Valley facilities which might 

otherwise be unable to operate under the lower limits. This change represents a 2% 

decrease from the existing limit, can be accomplished without significant impacts to 

existing operations, and has been demonstrated to be achieved-in-practice RACT for this 

category by operators in the South Coast and the Valley. 

The 90% VOC control efficiency requirement and the allowance for use of a vapor 

suppressed resin with a fifty (50) gram per square meter emission limit originated in 

SCAQMD Rule 1162 and have been subsequently adopted by other air districts. Like the 

proposed material VOC limits, Valley operators who would be subject to these proposed 

limits are already in compliance with the SCAQMD limits. 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT

Final Draft Staff Report: Rule 4684 August 18, 2011 

14 Final Draft Staff Report with Appendices 

 For Proposed Amendments to Rule 4684 

Because of the age of the current air districts’ rules, none of the other air districts have 

incorporated all of the limits which were found to be the most stringent. By incorporating 

all of the most stringent limits of the air districts and the CTG, Rule 4684 would be the 

most stringent rule possible for this category. Therefore, District staff concludes that the 

proposed amendments to Rule 4684 would satisfy, if not go beyond, RACT requirements 

for all polyester resin operations. 

XI. REFERENCES 

1. US EPA. 40 CFR Part 52, Federal Register, Vol. 75, No. 16, January 26, 2010. 

[EPA–R09–OAR–2009–0475; FRL–9104–7] 

2. US EPA. Technical Support Document for EPA’s Analysis of San Joaquin Valley 

Unified Air Pollution Control District’s Rule 4684, Polyester Resin Operations, May 

2009. 

3. South Coast Air Quality Management District (SCAQMD) Rule 1162 

4. Bay Area Air Quality Management District (BAAQMD) Rule 8-50 

5. Sacramento Metropolitan Air Quality Management District (SMAQMD) Rule 465 

6. Ventura County Air Pollution Control District (VCAPCD) Rule 74.14 

7. Mojave Desert Air Quality Management District (MDAQMD) Rule 1162